The Growth of Thin Lubricating Films of Plant Oils

The extreme conditions of high pressure and shear imposed in a lubricated sliding contact could influence tribochemical reactions that could occur over long sliding distances and time scales, possibly leading to changes in both friction and film thickness. Experiments conducted with 12 plant oils reveal for the first time, that thin lubricating films of some plant oils can grow to thicknesses much greater than what is predicted from either elastohydrodyamic theory or their adsorbed molecular heights. Some films grew as much as 25 times in thickness (unrefined canola oil), while others remained roughly unchanged (flaxseed and olive oil), or grew slightly and then collapsed during the test (safflower oil). The absence of a loss in film thickness and the viscoelastic-like behavior of the film when speeds are reduced to zero, support the view that polymerization could be the main mechanism of film growth. However, the lack of correlation between the degree of unsaturation and the film growth rate suggests that other mechanisms could also be at work.     

IPS-MAC: an informative preamble sampling MAC protocol for wireless sensor networks

Radio transceivers are the main source of energy consumption in wireless sensor networks (WSNs) where the source of energy supply is non-rechargeable battery. Several MAC protocols have been proposed in order to efficiently conserve energy in the link layer via duty-cycling. Low power listening (LPL) methods have been shown to outperform other schemes in lightly loaded situations which are common in environment monitoring applications. Nonetheless, as the network becomes dense, in LPL protocols such as BMAC a large number of nodes stay awake for each transmission, resulting in high levels of energy consumption. This paper introduces the informative preamble sampling (IPS) protocol in which a transmitter implicitly embeds information about its intended receiver via the power at which the preamble is transmitted. This results in far fewer nodes staying awake for each preamble. Upon hearing the preamble, a receiver executes a decision-making algorithm to decide whether to stay awake. If the decision-making algorithm is too lax, then more nodes stay awake following the preamble. On the other hand if the algorithm is too strict, it is likely that the intended receiver misses the preamble. In this paper we derive the optimal operating points for the IPS protocol. We show analytically that the IPS protocol can achieve a gain in energy by at least a factor of 2 over BMAC. We also conduct extensive simulations to show that IPS can achieve significant energy gains compared to BMAC.     

Canonical piecewise-linear analysis: Generalized breakpoint hopping algorithm

As an extension to the breakpoint hopping algorithm developed in reference 1, the algorithm presented in this paper efficiently solves the d.c. problem for finding the d.c. operating point(s) and for tracing the driving-point and transfer characteristics of an extremely broad class of non-linear resistive circuits. In particular, bipolar and MOS transistor circuits are included. A user-friendly C program has been written to implement this algorithm where the input format for describing the circuit is compatible with the SPICE program.     

Red-green-blue laser emissions from dye-doped poly(vinyl alcohol) films

A microscope slide acting as a passive waveguide was coated by three separate poly(vinyl alcohol) films that were doped with Coumarin 460, Disodium Fluorescein, and Rhodamine 640 perchlorate. On collinear pumping by a nitrogen laser, these dyes furnished primary red-green-blue laser emissions that were collected and waveguided by the microscope slide but exited from both ends. Frosting the waveguide exit introduced light scattering at the glass-air interface and spatially overlaid the red-green-blue laser emissions that emerged as a uniform white-light beam.     

The electro-adsorption chiller: a miniaturized cooling cycle with applications to micro-electronics

A novel modular and miniature chiller is proposed that symbiotically combines adsorption and thermoelectric cooling devices. The seemingly low efficiency of each cycle individually is overcome by an amalgamation with the other. This electro-adsorption chiller incorporates solely existing technologies. It can attain large cooling densities at high efficiency, yet is free of moving parts and comprises harmless materials. The governing physical processes are primarily surface rather than bulk effects, or involve electron rather than fluid flow. This insensitivity to scale creates promising applications in cooling personal computers and other microelectronic appliances.     

Detection of spatio-temporal conflicts on a temporal 3D space system

It is critical to detect the spatio-temporal conflicts in a project schedule, since many construction conflicts occur due to constraints in construction space and unavailability of intermediate functions of the in-progress building. This paper introduces a temporal 3D space system modelling method using a COmponent State network CEntric Model (COSCEM) to integrate such project aspects as product, process, space, and intermediate functions. Based on COSCEM, a 3D CAD model can be transformed into a temporal 3D space system. The concept of ‘existence vector’ and the Boolean logic operations are defined for depicting and deriving the dynamic characteristics of project entities. The procedures for detecting spatio-temporal conflicts are also presented. A case study of moving a truck crane on an excavated access road is selected to illustrate the proposed spatio-temporal detection methodology.     

Guest Editorial: Modeling Multimedia Information and Systems

Multimedia Tools and Applications -     

Comparison of newly isolated strains of Lactobacillus delbrueckii subsp. lactis for hydrogen peroxide production at 5 degrees C

Isolates of Lactobacillus delbrueckii subsp. lactis obtained from raw milk samples were compared for the ability to produce hydrogen peroxide (H2O2) at 5 degrees C. Nineteen out of 101 lactobacilli isolated were identified as L. delbrueckii subsp. lactis. The isolates of L. delbrueckii subsp. lactis from most raw milk samples produced more H2O2 than did isolates of other species of lactobacilli from the same samples. Seven isolates of L. delbrueckii subsp. lactis, which produced the highest levels of H2O2 at 5 degrees C were selected for comparison with a laboratory strain, L. delbrueckii subsp. lactis I. In 24 h, isolate RM2-5 produced 7.0 microg/10(9) cfu in buffer containing 5 mM sodium lactate and 4.4 microg/10(9) cfu in buffer containing 5 mM glucose. Three other isolates also produced more H2O2 on sodium lactate than on glucose. However, three remaining new isolates produced more H2O2 on glucose than on sodium lactate. All seven of the most active new isolates of L. delbrueckii subsp. lactis produced significantly higher concentrations of H2O2 than did L. delbrueckii subsp. lactis I in both solutions. Strain RM2-5 produced more H2O2 than did the other six most active newly isolated strains of L. delbrueckii subsp. lactis in this comparison.     

Stability analysis of generalized cellular neural networks

A rather general class of neural networks, called generalized cellular neural networks (CNNs), is introduced. the new model covers most of the known neural network architectures, including cellular neural networks, Hopfield networks and multilayer perceptrons. Several sets of conditions ensuring the input-output stability and global asymptotic stability of generalized CNNs have been obtained. the conditions for the stability of individual cells are checked in the frequency domain, while the stability of the overall network is analysed in terms of the stability of individual cells and the connectivity characteristics. the results on the global asymptotic stability are useful for the design of a generalized CNN such that the orbit of each state converges to a globally asymptotically stable equilibrium point which depends only on the input and not on the initial state. Such a network defines an algebraic map from the space of external inputs to the space of steady state values of the outputs and hence can accomplish cognitive and computational tasks.